2-benzimidazol(2)-benzofurans as optical brighteners

ABSTRACT

2-BENZIMIDAZOLS(2)-BENZOFURANS USEFUL AS OPTICAL BRIGHTENERS HAVE THE STRUCTURE   2-R6,3-R5,4-R1,5-R2,6-R3,7-R4-BENZOFURAN   WHEREIN R1 REPRESENTS HYDROGEN OR TOGETHER WITH R2 AND THE 2 CARBON ATOMS TO WHICH R1 AND R2 ARE ATTACHED, IT REPRESENTS BENZENE, R2 REPRESENTS HYDROGEN, HALOGEN OR TOGETHER WITH R1 AND THE 2 CARBON ATOMS TO WHICH R1 AND R2 ARE ATTACHED, IT REPRESENTS BENZENE. R3 REPRESENTS HYDROGEN, ALKYL COMPRISING 1 TO 4 CARBON ATOMS, OR ALKOXY COMPRISING 1 TO 4 CARBON ATOMS, R4 REPRESENTS HYDROGEN OR HALOGEN, R5 REPRESENTS HYDROGEN OR ALKYL COMPRISING 1 TO 4 CARBON ATOMS, OR PHENYL, R6 STANDS FOR THE FOLLOWING:   -C&lt;(-X-(4-R7-1,2-PHENYLENE)-N=)   WHEREIN X REPRESENTS NR-, WHEREIN R STANDS FOR HYDROGEN, ALKYL COMPRISING 1 TO 4 CARBON ATOMS, HYDROXYALKYL COMPRISING 1 TO 4 CARBON ATOMS, PHENYL OR BENZYL OR CYCLOHEXYL, AND R7 REPRESENTS HYDROGEN, ALKYL COMPRISING 1 TO 4 CARBON ATOMS, ALKOXY COMPRISING 1 TO 4 CARBON ATOMS OR HALOGEN.

United States Patent 3,772,323 2-BENZIMIDAZOL(2)-BENZOFURANS AS OPTICALBRIGHTENERS Hans Schlfipfer, Base], and Guglielmo Kabas, Binningeu,

Basel-Land, Switzerland, assignors to Ciba-Geigy Corporation, Ardsley,N.Y. No Drawing. Filed June 12, 1970, Ser. No. 45,922 Int. Cl. C07d49/38 US. Cl. 260--309.2 6 Claims ABSTRACT OF THE DISCLOSUREZ-benzimidazols(2)-benzofurans useful as optical brighteners have thestructure l s R,

Ra Ra l (I) wherein wherein X represents NR, wherein R stands forhydrogen, alkyl comprising 1 to 4 carbon atoms, hydroxyalkyl comprising1 to 4 carbon atoms, phenyl or benzyl or cyclohexyl, and

R represents hydrogen, alkyl comprising 1 to 4 carbon atoms, alkoxycomprising 1 to 4 carbon atoms or halogen.

DESCRIPTION OF THE INVENTION The present invention relates to newbenzofuran compounds, to their use for the optical brightening oforganic materials and the compositions thereof.

It has been found that compounds of the following Formula I are able tooptically brighten organic materials.

In the above formula,

R represents hydrogen, a lower alkyl group, or together with R and the 2carbon atoms to which R and R are attached it represents a benzeneradical,

ice

R represents hydrogen, a lower alkyl group or alkoxy group, halogen, acarboxy, a carbalkoxy, an aminocarbonyl, a monoor dialkylaminocarbonyl,a sulphonic acid, an alkylsulphonyl, an alkyloxysulphonyl, anaminosulphonyl or a monoor dialkylaminosulphonyl group or together withR and the 2 carbon atoms to which R, and R are attached, it represents abenzene radical,

R represents hydrogen or a lower alkyl group or alkoxy group or togetherwith R and the 2 carbonatoms to which R and R are attached, itrepresents a benzene radical,

R, represents hydrogen, a lower alkyl group or halogen, or together withR and the 2 carbon atoms to which R and R are attached, it represents abenzene radical,

R represents hydrogen, a lower alkyl group, or the phenyl group, and

R stands for one of the following groups:

wherein X represents oxygen or an NR- group, wherein R stands forhydrogen, a lower alkyl group or hydroxyalkyl group, having at least 2carbon atoms, a phenyl group optionally substituted by halogen, loweralkyl group or alkoxy group; an araliphatic group, a cyclopentyl groupoptionally substituted, or a cyclohexyl group optionally substituted,and

R represents hydrogen, a lower alkyl group or alkoxy group, the phenylgroup, or halogen;

Rn wherein Rn r 3? --0 dun R13 CH1 wherein R and R represent hydrogen,fluorine, chlorine, or a carboxy, a carbalkoxy, an aminocarbonyl, amonoor dialkylaminocarbonyl, a sulphonic acid, an alkylsulphonyl, analkyloxysulphonyl, an aminosulphonyl, a monoor dialkylaminosulphonylgroup.

In some cases the new compounds have an optical brightening action manytimes greater than that of already known benzofuran compounds, andparticularly outstanding in this respect are the benzofurans of FormulaI wherein R denotes the groups Particularly good effects are shown bythe benzofurans of Formula I, wherein R represents hydrogen or togetherwith R and the 2 carbon atoms to which R and R are attached, itrepresents a benzene radical,

R represents hydrogen, halogen, or together with R and the 2 carbonatoms to which R and R are attached, it represents a benzene radical,

R represents hydrogen, an alkyl group comprising 1 to 4 carbon atoms, oran alkoxy group comprising 1 to 4 carbon atoms,

R represents hydrogen or halogen,

R represents hydrogen or an alkyl group comprising 1 to 4 carbon atoms,or the phenyl group,

R stands for one of the following groups:

wherein,

H Rs

I a") LC/ wherein R and R represents hydrogen, or together and with the2 carbon atoms to which R and R are attached, they represent a benzeneradical, and

R represents hydrogen, an alkyl group comprising l to 4 carbon atoms, oran alkoxy group comprising 1 to 4 carbon atoms, and

1: Q (iIHz wherein R and R represent hydrogen or chlorme.

Most preferred are compounds of Formula I wherein R is hydrogen ortogether with R and the 2 carbon atoms to which R and R are attached, itrepresents a benzene radical,

wherein,

X represents oxygen or an NR- group, wherein R stands for hydrogen,methyl, cyclohexyl, phenyl or benzyl, and

R represents hydrogen, chlorine or methyl wherein R and R representhydrogen or together and with the 2 carbon atoms to which they areattached the benzene radical, and

R represents hydrogen or methoxy,

If in the compounds of Formula I, R R and R, are halogen, they are forexample chlorine or fluorine. If R R R and R and the substituent of theamino group X are alkyl, then it can be methyl, ethyl, propyl, n-butylor iso-butyl. If R R and R are alkoxy groups they can be methoxy,ethoxy, propoxy or butoxy. If the amino group X is substituted byhydroxyalkyl it can be hydroxyethyl, hydroxypropyl or hydroxybutyl.

The new compounds have, moreover, a wide field of application. Inparticular, they are used for the brightening of textile materials,particularly synthetic textile material, of various kinds, such as wool,cotton and synthetic or semi-synthetic fibres, e.g. those made frompolyesters such as polyterephthalic acid glycol esters, polyolefius suchas polypropylene and polyethylene, polyamides such as nylon 6 and nylon66, polyvinyl chloride and cellulose esters such as cellulose-2/2-acetate and cellulose triacetate, and especially those made frompolyacrylonitrile.

The organic material can be brightened, for example, by incorporatinginto it small amounts of optical brighteners according to the invention,preferably 0.001 to 1% relative to the material to be brightened,optionally together with other substances such as softeners, stabilisersor pigments. The brighteners may be worked into the synthetic materials,e.g. dissolved in softeners such as dioctylphthalate, or together withstabilisers such as dibutyl tin laurate or sodiumpentaoctyltripolyphosphate, or together with pigments, e.g. titaniumdioxide. Depending on the nature of the material to be brightened, thebrightener can also be dissolved in the monomers before polymerisation,in the polymer mass, or together with the polymers. in a solvent. Thematerial preliminary treated in thisv manner is afterwards brought intothe desired ultimateform by methods known per se, such as calendering,pressing, extrusion, coating, moulding and, in particular, spin ning andstretching. It is also possible for the brighteners to be worked intofinishings, e.g. into finishings for textile fibres such as polyvinylalcohol, or into resins or resin pre-condensates such as, e.g. methylolcompounds of ethylene urea, which are used for the treatment oftextiles.

Preferably, however, colourless, high-molecular, organic material isbrightened in the form of fibres. For the brightening of these fibrematerials, an aqueous solution or dispersion of benzofurans of Formula Iaccording to the invention is advantageously used. The brightenerdispersion or solution preferably has, relative to the fibre material, acontent of 0.005-0.5% of benzofuran according to the invention. Inaddition, the dispersion can contain auxiliaries such as dispersingagents, e.g. condensation products of fatty alcohols or alkylphenolscontaining to 18 carbon atoms, with to 25 moles of ethylene oxide, orcondensation products of alkylmonoor polyamines containing 16 to 18carbon atoms, with at least 10 moles of ethylene oxide, organic acidssuch as formic, oxalic or acetic acid, detergents, swelling agents suchas dior trichlorobenzenes, wetting agents such as sulphosuccinic acidalkyl esters, bleaching agents such as sodium chlorite, peroxides orhydrosulphites, as well as, optionally, brightening agents of otherclasses such as, e.g. derivatives of stilbene having afiinity tocellulose.

The brightening of the fibre material with the aqueous brightener liquoris performed either by the exhaust process, at temperatures preferablyof 30 to 150 C., or by the padding process. In the latter case, thematerial is impregnated, for example, with a 0.2-0.5% brightenerdispersion, and is then finished, e.g. by a dry or moist heat treatment,e.g. by steaming at 2 atm. or, after drying is completed, by a short dryheating to 180 to 220, whereby the fabric is optionally simultaneouslythermofixed. The fibre material treated in this manner is finally rinsedand dried.

Colourless, high-molecular, organic material optically brightenedaccording to the invention, particularly the natural or synthetic fibrematerial brightened by the exhaust process, has a pleasing, pure white,blue-violet to bluish fluorescent appearance; such material dyed inlight shades and brightened according to the invention is distinguishedby a pure shade. Benzofurans of Formula I can also be added todetergents; these can be used for the brightening of textiles. Thedetergents can contain the usual fillers and auxiliaries, e.g.alkali-polyand -polymetaphosphates, alkali silicates, alkali borates,alkali salts of carboxymethyl celluloses, foam stabilisers such asalkanolamides of higher fatty acids, or complexones such as solublesalts of ethylenediaminetetraacetic acid, ordiethylenetriaminepentaacetic acid, as well as chemical bleachingagents, such as perborates or percarbonates.

The new benzofurans are worked into the detergents or into washingliquors advantageously in the form of their solutions in water, or inneutral, water-miscible and/or readily volatile organic solvents such aslower alkanols, lower alkoxyalkanols or lower aliphatic ketones. Theymay, however, also be used in a finely dispersed form solid form, ontheir own or in admixture with dispersing agents. For example, they canbe mixed, kneaded or milled with the wash-active substances; and thenthe usual auxiliaries and fillers added. The brightening agents are, forexample, stirred together with the wash-active substances, the usualauxiliaries and fillers, and water, to form a slurry, and this is thensprayed in a spray drier. The new benzofuran derivatives may also beadded to finished detergents, e.g. by spraying a solution in a readilyvolatile and/or Water-soluble organic solvent on to the dry detergentsas these are kept in motion.

The content in the detergents of optical brightener of Formula I is'advantageously 0.001 to 5%, relative to the solid content in thedetergent.

Washing liquors containing the benzofurans of Formula I impart, duringwashing, to the textile fibres treated therewith, e.g. cotton orsynthetic polyamide, polyester, polyolefin and cellulose ester fibres, abrilliant appearance in daylight.

The compounds according to the invention can be produced by knownmethods from known starting materials.

Compounds of Formula I wherein R represents the optionally substitutedbenzimidazolyl group, are produced, e.g. by starting with optionallysubstituted o-nitroaniline and acylating this with optionallysubstituted coumarilic acid, or with a functional derivative thereof;then reducing the nitro group in an acid medium, e.g. with stannouschloride; and simultaneously effecting ring closure to the imidazolering.

The compounds can also, for instance, be produced fromN-mono-substituted o-phenylenediamines, by acylating the latter withoptionally substituted coumarilic acid or a functional derivativethereof and performing ringclosure in the correspondingly substitutedprimary acyl-ophenylenediamine in the presence of acid condensationagents such as hydrochloric acid.

If, instead of o-nitroaniline, optionally substituted o-aminophenol isacylated, and the acylation product heated with the further splitting01f of water, then compounds of Formula I are obtained, wherein Rrepresents a benzoxazolyl group.

Compounds of Formula I wherein R represents the optionally substitutedbenzofuran 2 yl oxdiazol-2-yl group can be produced by reactingoptionally substituted benzofuran-Z-carboxylic acid hydrazide withoptionally substituted benzofuran-Z-carboxylic acid chloride, andeffecting in the obtained product, in the presence of acid condensationagents such as phosphorus oxychloride or thionyl chloride, ring closure.

Compounds of Formula I with the substituent R representing apyrazoli-n-3-yl group substituted in the 1-position by an optionallysubstituted phenyl group can be produced, e.g. by reacting a2-(w-aminopropionyl)-benzofuran disubstituted on the amino group with anoptionally substituted phenyl hydrazine, in the presence of alkalineagents.

For the introduction of water-solubilising groups such as, e.g. SO H-groups, the benzofuran derivatives can be subsequently treated withsulphonating agents such as, e.g. H mixtures of H SO +SO orchlorosnlphonic acid. Such sulphonic acids are particularly suitable forthe brightening of cellulose substrates or polyamide from an acid bath.

The temperatures are given in degrees centigrade in the followingexamples.

EXAMPLE 1 (1.1) 6-methoxy-2-[benzimidazolyl (2)] benzofuran: To asolution of 14.5 g. of o-nitroaniline in 200 ml. of pyridine are addedat room temperature within 2030 minutes, whilst stirring is maintained,21.05 g. of 6- methoxycoumarilic acid chloride (B.P. 171-173"). Themixture heats up thereby to ca. 40 and the acylation productprecipitates already partly in crystalline form. After one hour offurther stirring, the reaction mixture is heated, to complete thereaction, for a further one hour to 80-85, and is then allowed to coolwhilst stirring proceeds. From the reaction solution crystillises out6-methoxycoumaric acid-o-nitroanilide, which is filtered off, washedwith ethanol and dried, M.P. 172-173".

31.2 g. of 6-methoxycoumarilic acid-o-nitroanilide are suspended in 1100ml. of ethylene glycol monomethyl ether, and the suspension is heated to80. To the suspension is added dropwise at 8090, Within 25 minutes, asolution of 107.0 g. of tin-II-chloride-2H O in 205 ml. of 37.3%hydrochloric acid. Accompanied by a slight rise in temperature, a clear,fluorescent solution is formed.

The solution is subsequently refluxed for 3 hours at 104- 106 in areflux condenser; it is allowed to cool to ca. 50 and is then pouredinto a mixture of 1250 ml. of 30% sodium hydroxide solution and 3400 ml.of water; the obtained solution is separated from the solvent by beingintensively concentrated by evaporation in vacuo. The product herebyprecipitating is filtered ofl under suction, washed with water untilfree of alkali, and dried. After crystallisation twice fromwater/ethanol (2:3), with the addition of decolourising carbon black,6-methoxy-2-[benzimidazolyl-(2)]-benzofuran is obtained in the form ofcolourless shining crystals which contain /2 mol of crystal water andmelt at 233233.5.

The new compound dissolves in ethanol with a blueviolet fluorescence indaylight, the fluorescence becoming appreciably more intense with theaddition of inorganic or organic acids.

The compound is particularly suitable for the brightening ofpolyacrylonitrile fibres.

(1.2) If, instead of o-nitroaniline, the equivalent amount of2-nitro-4-chloroaniline is used, the procedure being otherwise asdescribed in the example, then 6-methoxy 2 ([5 chlorobenzimidazolyl-(2)]-benzofuran is obtained which, after recrystallisation from benzene, isobtained in the form of colourless flakes which melt at 220-2215". Thisproduct possess properties similar to those of the above describedcompound.

(1.3) If, instead of o-nitroaniline, the equivalent amount of4-methoxy-2-nitroaniline is used, the procedure being as described inthe example, then fi-methoxy- 2-[S-methoxybenzimidazolyl-(2)]-benzofuran is obtained. This product possesses properties similar tothose of the above described compounds.

EXAMPLE 2 (2.1) 4,5-benzo-2-[benzimidazolyl- (2) ]-benzofuran: To asolution of 14.5 g. of o-nitroaniline in 220 ml. of pyridine are addedat room temperature within 30 minutes, whilst the solution is beingstirred, 23.05 g. of finely powdered 4,5-benzocoumarone-2-carboxylicacid chloride. The mixture heats up thereby to ca. 4045, and theacylation product already partly crystallises out. After 30 minutesfurther stirring, the reaction mixture is heated for 1 hour to 90-95,and the thin suspension is then poured on to a large amount of water.The obtained precipitate is filtered off under suction after 1-2 hours,washed with water and ethanol, and then dried. In this manner areobtained 29.4 g. of practically pure 4,S-benzocoumarone-Z-carboxylicacid-o-nitroanilide, M.P. 229-230. An analytical sample recrystallisedfrom acetic acid melts at 231-231.5.

26.2 g. of the above described acylation product are stirred togetherwith 880 ml. of ethylene glycol monomethyl ether, and to this are addedat 80-90 within minutes 83.4 g. of tin-II-chloride-2H O dissolved in 163ml. of 37.3% hydrochloric acid. The reaction mixture is subsequentlystirred for 3 hours at 104106; it is then poured, after cooling, on to amixture of 980 ml. of 30% sodium hydroxide solution and 2700 ml. ofwater; and, under reduced pressure, the ethylene glycol monomethyl etheris for the most part azeotropically distilled off with water, wherebythe compound precipitates towards the end of distillation. Aftercooling, the pale-yellow-brown precipitate is filtered off with suction,washed with water and repeatedly recrystallised from aqueous ethanol.4,5- benzo-2-[benzimidazolyl-(Z)]-benzofuran is obtained in the form ofpractically colourless, spherical crystals containing /2 mol of crystalwater and which sinter at ca. 145 and then melt at 231232.5.

The new compound dissolves in ethanol with a blueviolet fluorescence indaylight, the fluorescence becoming more intense with the addition ofinorganic or organic acids.

The compound is particularly suitable for the brightening ofpolyacrylonitrile fibres.

The following benzofuran derivatives can be obtained in an analogousmanner:

(2.2) From 5-chlorocoumarilic acid-o-nitroanilide, S-chloro-Z-[benzimidazolyl-(Z) ]-benzofuran, M.P. 254- 256.

(2.3) From 5-chlorocoumarilic acid-(4-chloro-2-nitro)- anilide,5-chloro-2- [5-chlorobenzimidazolyl-(2) ]-benzofuran, M.P.186-188".

(2.4) From 5,7-dichlorocoumarilic acid-o-nitroanilide, 5,7-

dichloro-Z-[benzimidazolyl-(2) ]-benzofuran, M.P. 281- 282.

(2.5) From 5,7-dichlorocoumarilic acid-(4-chloro-2- nitro) -anilide,5,7-dichloro-2- [S-chlorobenzimidazolyl- (2) ]-benzofuran, M.P. 251252.

(2.6) From 6-methoxy-3-methylcoumarilic acid-o-nitroanilide,6-methoxy-3-methyl-2-[benzimidazolyl-(Z)]- benzoturan.

(2.7) From 6-methoxy-3-phenylcoumarilic acid-o-nitroanilide, 6-methoxy-3-phenyl-2- [benzimidazolyl- (2) benzofuran.

EXAMPLE 3 CHaO J-C 3.1) 6-methoxy-2-[ 1-methylbenzimidazo1yl-( 2)]-benzofuran: To a solution of 7.6 g. of N-methyl-o-nitroaniline in 85ml. of pyridine are added at room temperature, during the course of 10minutes, 10.5 g. of 6- methoxy-coumarilic acid chloride. The reactionmixture is stirred for 3 hours at room temperature; it is heated for 1hour to -85 and then poured into water, whereby the acylation productfirstly precipitates as oil which crystallises after a short time. Afterdrying and recrystallisation once from benzene/petroleum ether,6-methoxycoumarilic acid-N-methyl-o-nitroanilide is obtained in the formof practically colourless, cube-shaped crystals which melt at105.5-106.5.

13.0 g. of the above described acylation product are stirred togetherwith 400 ml. of ethylene glycol monomethyl ether, and to the mixture areadded at 8090' within 15 minutes 42.0 g. of tin-II-chloride-2H Odissolved in 84 ml. of 37.3% hydrochloric acid, The reaction mixture issubsequently stirred for 3 hours at 104-106; it is then poured, aftercooling, into 1800 ml. of 10% sodium hydroxide solution; and from theobtained solution, under reduced pressure, ethylene glycol monomethylether is azeotropically distilled off with water, whereby the compoundprecipitates towards the end of distillation. After cooling, the productis separated, washed with water, and dried. By means of repeatedrecrystallisation from chloroform/petroleum ether (1:2) is obtained6-methoxy- 2-[l-methylbenzimidazolyl-(2)]-benzofuran in the form ofpractically colourless crystals which melt at 151- 151.5".

The new compound dissolves in ethanol with a blueviolet fluorescence indaylight, the fluorescence becoming appreciably more intense with theaddition of inorganic or organic acids.

The compound is particularly suitable for the brightening ofpolyacrylonitrile fibres.

The same compound is also obtained by methylating the benzimidazoleobtainable according to Example 1 in methanolic solution in the presenceof alkali hydroxide with dimethyl sulphate or methyl iodide.

(3.2) If, instead of 6-methoxycoumarilic acid chloride, the equivalentamount of 4,5-benzocoumarone-2-carboxylic acid chloride is used, withthe procedure otherwise as described in the example, then4,5-benzo-2-[l-methyl benzimidazolyl-(Z)J-benzofuran is obtained which,after recrystallisation from ethanol, is in the form of colourlesscrystals which melt at 208-209". This product possesses propertiessimilar to those of the above described compound, and is thereforeparticularly suitable for the brightening of polyacrylonitrile fibres.

EXAMPLE 4 (4.1) 6-methoxy 2 [benzoxazolyl-(2)]-benzofuran: 24.0 g. of6-methoxycoumarilic acid and 13.6 g. of oaminophenol are refluxed in 450ml. of xylene in the presence of 0.5 g. of boric acid for 26 hours in areflux condenser, whilst stirring is maintained; the formed water beingcontinuously separated by means of a water-separator. After cooling, theacylamino compound is filtered off and washed with ethanol. Aftercrystallisation from ethanol, with the addition of decolourising carbonblack, 22.6 g. of practically colourless, feather-like crystals of6-methoxycoumarilic acid-o-hydroxyanilide are obtained, which melt at229'-229.5.

6.0 g. of finely powdered acylamino compound are intimately mixed with18.0 g. of anhydrous zinc chloride, and heated, with the exclusion ofmoisture, during 20-30 minutes in an oil-bath at 200 205. A dark greenmelt is hereby formed which, after cooling, completely solidifies. Themelt is pulverised and then stirred with 200 ml. of water for 1 /2 hoursat 50-60; and the pH-value is adjusted to 35 by the addition ofhydrochloric acid. The product is thereupon filtered under suction,washed with water, and dried. After recrystallisation three times fromethanol, 6-methoxy-2-[benzoxazolyl-(2)]-benzofuran is obtained in theform of slightly flesh-coloured crystals which melt at 144.5-145 andwhich have a pale violet fluorescence in ultraviolet light.

The compound possesses good affinity to polyacrylonitrile fibres, and istherefore suitable for the brightening of these fibres.

The following benzofuran derivatives can be produced in an analogousmanner:

CH: O

(4.2) From 6-methoxycoumarilic acid and m-amino-pcresol, 6-methoxy-2-[S-methylbenzoxazolyl-(2) benzofuran, M.P. 128128.5.

(4.3) From 4,S-benzocoumarone-2-carboxylic acid and o-aminophenol,4,5-benzo-2- [benzooxazolyl-(2) 1- benzofuran, M.P. 172.5-173".

(4.4) From 4,5-benzocoumarone-2-carboxylic acid and m-amino-p-cresol,4,5-benzo-2-[S-methylbenzoxazolyl- (2)]-benzofuran, M.P. 194.5195.

EXAMPLE acid chloride are then added, which rapidly dissolve with aslight rise in temperature. Stirring afterwards proceeds for 2 hours,the reaction mixture is heated for of an hour to -85 and is then pouredinto water, whereby the reaction product precipitates in crystallineform. After separation and washing with water, the product is dried invacuo. In this manner are obtained 22.6 g. of crudebis-(6-methoxybenzofuran-2-carboxy) hydrazide. After recrystallisationfrom acetic ester, colourless crystals are obtained which melt at208-209.

20.0 g. of crude bis-(6-methoxybenzofuran-2-carboxy)- hydrazide areintroduced at room temperature, Whilst stirring is maintained, into 80ml. of phosphorous oxychloride. The suspension is heated to 90 andstirred .for 4 hours at this temperature, whereby a light-brown, clearsolution is gradually formed. The somewhat cooled reaction mixture isthereupon poured, with stirring, onto ice/water and, after completeddecomposition of excess phosphorus oxychloride, the precipitated productis filtered under suction, washed with water until the reaction obtainedis neutral, and dried. After crystallization twice from acetic ester,with the addition of decolourising carbon black, 13.9 g. of2,5-bis-[6-methoxybenzofuranyl- (2)]-1,3,4-oxadiazole are obtained inthe form of flat crystal-platelets which melt at 225-225.5.

A solution of the new 1,3,4-oxadiazole in acetic acid is colourless andexhibits in daylight an intense blue-violet fluorescence.

The compound possesses good afiinity to polyamide and polyester fibers,and is therefore particularly suitable for the brightening of thesesubstrates.

In an analogous manner, it is possible to produce from (5.2) bis(4,5-benzocoumarone-Z-carboxy)-hydrazide,2,5-bis[4,5-benzocoumaronyl-(2)] 1,3,4 oxadiazole M.P. 271-271.5.

EXAMPLE 6 A suspension of 12.7 g. ofw-dimethylamino-2-propionylbenzofuran hydrochloride, 9.3 g. of3-chlorophenylhydrazine, 16 g. of sodium carbonate, ml. of ethanol and70 ml. of water is refluxed for 8 hours. The reaction mixture isthereupon cooled, filtered under suction, washed with water and dried.After recrystallization twice from a mixture of benzene and hexane areobtained, with the aid of bleaching earth, 10 g. (corresponding to 67.5%of the theoretical value) of1-(3-chlorophenyl)-3-(-benzofur-2-yl)-pyrazoline, M.P. 118-l19(uncorrected), absorption ax 374 nm. If, instead of w-dimethyIamino-Z-propionylbenzofuran hydrochloride, w-dimethyIamino-Z-propionyl-5-chlorobenzofuran hydrochloride is used, with the procedureotherwise as described above, then a compound of the formula:

is obtained, M.P. 129131 (uncorrected), absorption a 380 nm.

The w-dimethylamino-2-propionylbenzofuran hydrochloride used as startingmaterial can be produced as follows:

A mixture of 16 g. of 2-acetylbenzofuran, 12.2 g. of dimethylaminehydrochloride, 3.6 g. of paraformaldehyde, 30 ml. of ethanol and 0.3 ml.of concentrated hydrochloric acid is refluxed for 5 hours. The mixtureis then cooled to room temperature, the obtained crystalline pre- 1 lcipitate filtered under suction, washed wtih cold ethanol, and dried. Inthis manner are obtained 17.8 g. (corresponding to 70.5% of thetheoretical value) of w-dimethylamino-2-propionylbenzofuranhydrochloride, M.P. 201- 203.

If, instead of 2-acetylbenzofuran, 2-acetyl-5-chlorobenzofuran is used,with otherwise the same procdure as described above, thenw-dimethylamino-Z-propionyl-5- chlorobenzofuran hydrochloride, M.P.173175, is obtained.

EXAMPLE 7 (7.1) 6 methoxy 2 [1 phenyl benzimidazolyl- (2)]-benzofuran:21.7 g. of 6-methoxycoumarilic acid chloride are quickly added withstirring at room temperature to a solution of 18.4 g. ofZ-amino-diphenylamine in 200 m1. of pyridine. The temperature of thereaction mixture rises to about 45. After 15 minutes the reactionmixture is heated for another hour at 8085 to complete the reaction. Thedark solution is then poured into a generous amount of water. Theprecipitated brown rose colored acylation product which is at firstslimy, solidifies after several hours and is then separated by suctionfiltration, washed with water and dried. After recrystallization fromethanol, 31.5 g. (88% of theory) of2-[6-methoxycoumaroylamido]-diphenylamine are obtained. M.P. 14l142.

17.9 g. of 2-[G-methoxycoumaroylamido]-diphenylamine are stirred in 180ml. of ethylene glycol monomethyl ether, treated with 15.0 g. of 37.3%hydrochloric acid, and the reaction mixture is heated to 100-105 andgently refluxed for 4 hours at this temperature. The stronglyfluorescing reaction solution is then poured into a mixture of 18 ml. of30% sodium hydroxide solution and 1800 ml. of water, thus precipitatingthe reaction product which is somewhat slimy at first. After standingfor several hours, the solidified product is separated, pulverized,washed with water until free of alkaline and dried. 14.6 g. (85.8% oftheory) of dark brown red crystals having a melting point of 151-155 areobtained. By recrystallizing from toluene, and treating withdecolorizing carbon and bleaching earth, the compound of the aboveformula is obtained as almost colorless crystals 7 having a meltingpoint of 161162.

3 equivalent amount of N-cyclohexyl-l,2-phenylenediamine orN-benzyl-l,Z-phenylenediamine and otherwise the procedure described inthe example is followed,

(7.2) 6 methoxy 2 1 cyclohexyl benzimidazolyl- (2)-benzofuran, or

(7.3) 6 methoxy 2 1 benzyl benzimidazolyl (2)- benzofuran,

having similar properties is obtained.

EXAMPLE 8 To 100 ml. of water are added 0.12 ml. of 85% formic acid and0.6 g. of alkylpolyglycol ether. A solution is prepared of the opticalbrightener according to Example 1.1 by dissolving 1 g. thereof in 1000ml. of ethylene glycol monomethyl ether. 1.5 ml. of this stock solutionare added to the above described solution. The thus obtained liquor isheated to 60, and 3 g. of polyacrylonitrile fabric are introduced. Thetemperature is raised within 10-15 minutes to 95-98 and this temperatureis maintained for 1 hour. The fabric is then rinsed for 2 minutes inrunning water, and subsequently dried for 20 minutes at 60. The thustreated fabric has a white, bri1- liant appearance.

By proceeding as described in the above example but using, instead ofthe brightener given there, the compounds described in the Examples 1.2,2, 3, 4 and 7, whereby only 0.75 ml. of the brightener stock solution ofthe compounds of Example 4 are used, similar results are obtained.

EXAMPLE 9 To 100 ml. of water are added 0.2 g. of sodium nitrate, 0.2 g.of sodium chlorite, 0.2 g. of oxalic acid or an equivalent amount ofanother organic or inorganic acid suitable for this purpose, as well as0.06 g. of alkylpolyglycol ether. A solution is prepared of thebrightener according to Example 3.1 by dissolving 1 g. of the statedbrightener in 1000 ml. of ethylene glycol monomethyl ether. 1.5 ml. ofthis stock solution are added to the above described solution. Thisliquor is heated to 60; 3 g. of polyacrylonitrile fabric are then added,the temperature is raised within 10-15 minutes to -98, and the bath isallowed to stand for 60 minutes at this temperature. The fabric is thenrinsed in cold water and dried for 20 minutes at 60. The thus treatedfabric has a white, brilliant appearance.

Similar results are obtained with the procedure as de scribed above butusing the brighteners given in Example 1, 2.1, 3.2 or 7.1.

EXAMPLE 10 To ml. of water are added 0.2 g. of sodium sulphate and 0.06g. of alkylpolyglycol ether. A solution is prepared of the opticalbrightener according to Example 4.1 by dissolving 1 g. thereof in 1000ml. of ethylene glycol monomethyl ether. An amount of 2 ml. of thisstock solution is added to the above described solution, and theobtained liquor is heated to 40-45 3 g. of prebleached cotton fabric arethen introduced into the solution, and the material is treated at thistemperature for 30 minutes. The fabric is afterwards rinsed for 2.minutes in running Water, and subsequently dried for 20 minutes at 60.The thus treated fabric has a pleasing white appearance.

Similar results are obtained by using, with otherwise the same procedureas described above, the brighteners given in Example 1, 2, 3, 4.2, 4.3,4.4, 5, or 7.

EXAMPLE 11 To 100 ml. of water are added 0.4 g. of detergent of thefollowing composition:

Instead of sodium sulphate, the detergent can also contain 10-20% ofsodium perborate or some other oxygenreleasing agent.

1 g. of the optical brightener obtainable according to Example 4.3 isdissolved in 1000 ml. of ethylene glycol monomethyl ether. An amount of2 ml. of this stock solution is added to the above described aqueoussolution. The thus obtained washing liquor is heated to 60, and 3 g. ofa pre-bleached cotton fabric are introduced into the liquor. Thetemperature is raised within 10-15 minutes to 92 and the bath is allowedto stand for 30 minutes at this temperature. The fabric is subsequentlyrinsed and dried. The fabric treated in this manner has a white andbrilliant appearance.

Similar results are obtained by proceeding as described above but using,instead of the above brightener, the brightener described in Example 1,2, 3, 4.1, 4.2, 4.4, 5, or 7.

EXAMPLE 12 To 100 ml. of water are added 0.2 g. of trichlorobenzene ascarrier, and to this is added a solution of 0.0015 g. of the oxadiazoledescribed in Example 5.1, in 1.5 ml. of dimethylformamide. The thusobtained liquor is heated to 60, and 3 g. of a polyester fabric areintroduced into the liquor. The temperature is raised within -15 minutesto 95-98 and the liquor is allowed to stand at this temperature for 1hour. The fabric is then rinsed for 2 minutes in running water, and issubsequently dried for 20 minutes at 60. The fabric treated in thismanner has a white, brilliant appearance.

A similar result is obtained by using the brightener ac cording toExample 5.2.

In this example and in the following Examples 13 and 15, the expressiontrichlorobenzene as carrier signifies a mixture consisting of 76 partsof 1,2,4-trichlorobenzene and 27 parts of a mixture of suitableemulsifiers.

EXAMPLE 13 To 290 ml. of water are added 0.15 ml. of trichloro benzeneas carrier, and 0.3 ml. of alkylpolyglycol ether. A solution is preparedof the optical brightener according to Example 5.2 by dissolving 1 g. ofthe said optical brightener in 1000 ml. of dimethylformamide. An amountof 7.5 ml. of this stock solution is added to the above describedsolution. The aqueous dispersion containing the optical brightener isheated to 60; and g. of polyester fabric are introduced into thesolution. The temperature is raised within 15-20 minutes to 130 and thefabric is left at this temperature for 30 minutes, whereupon thetemperature is lowered within 10-15 minutes to 60. The fabric is thenrinsed for 2 minutes in running water, and subsequently dried forminutes at 60. The thus treated fabric has a white and brilliantappearance.

A similar result is obtained by using, with otherwise the same procedureas described above, the brightener according to Example 5.1.

EXAMPLE 14 A solution is produced of the optical brightener according toExample 5.1 by dissolving -l g. thereof in 1000 m1. ofdimethylformamide. A polyester fabric is padded at 20 with this solution(squeezing effect 50-60%, rollerpressure 30 kg./cm. speed: 3 m./minute).The fabric is dried for 20 minutes at 60 and afterwards fixed for 30seconds at 200. The thus treated fabric has a white, brilliantappearance.

A similar result is obtained by using, with otherwise the same procedureas described above, the brightener according to Example 5 .2.

EXAMPLE 15 To 290 ml. of water are added 0.3 ml. of alkylpolyglycolether and 0.15 ml. of trichlorobenzene as carrier. A stock solution isprepared of the optical brightener according to Example 5.2 bydissolving 1 g. of the said optical brightener in 1000 ml. ofdimethylformamide. 4.5 ml. of this stock solution are added to the abovedescribed solution. This aqueous dispersion containing the brightener isheated to 60; 15 g. of polyester fabric are then introduced into thisliquor, and the temperature is raised within 15-20 minutes to 130. Thefabric is left at this temperature for 30 minutes, whereupon the 14temperature is lowered within 10-15 minutes to 60. The fabric is thenrinsed for 2 minutes in cold running water, and afterwards dried for 20minutes at 60. The dry fabric is subsequently thermofixed for 30 secondsat 200. After this treatment, the fabric has a white, brilliantappearance.

A similar result is obtained by using the brightener according toExample 5.1, with the procedure otherwise as described above.

EXAMPLE 16 To 100 ml. of water are added 0.4 g. of detergent as given inExample 10. A solution is prepared of the optical brightener accordingto Example 5.1 by dissolving 1 g. thereof in 1000 ml. ofdimethylformamide. An amount of 0.8 ml. of this stock solution is addedto the above described washing liquor, and this is heated to 60. Intothis liquor are then introduced 3 g. of polyester fabric, and this istreated for 30 minutes at this temperature. The fabric is then rinsed asusual, and dried. The thus treated fabric is clearly brightened.

A similar result is obtained by using the brightener according toExample 5.2, with the procedure otherwise as described above.

EXAMPLE 17 To 100 ml. of water are added 0.06 g. of alkylpolyglycolethcr. A solution is prepared of the optical brightener according toExample 4.3 by dissolving 1 g. thereof in 1000 ml. of ethylene glycolmonomethyl ether. An amount of 3 ml. of this stock solution is added tothe above described solution. This aqueous liquor containing thebrightener is heated to 60, and 3 g. of nylon fabric are introduced intothe liquor. The temperature is raised within 10-15 minutes to 92-95, andthe fabric is left at this temperature for 30 minutes. After rinsing anddrying, the thus treated material has a white and brilliant appearance.

Similar results are obtained with the brighteners according to Example5.

EXAMPLE 18 To 100 ml. of water are added 0.12 ml. of formic acid and0.06 g. of alkyl polyglycol ether. A solution is prepared of the opticalbrightener according to Example 4.3 by dissolving 1 g. thereof in 1000ml. of ethylene glycol monomethyl ether. 3 ml. of this stock solutionare added to the above described aqueous solution. The aqueous liquorcontaining the brightener is heated to 60; 3 g. of nylon fabric are thenintroduced, and the temperature is raised within 10 15 minutes to 92-95,whereupon the liquor is left for 30 minutes at this temperature. Thefabric is then rinsed and dried. The thus treated fabric has a white andbrilliant appearance.

Similar results are obtained with the brighteners described in Examples4.4 and 5, using the same method of application, wherebydimethylformamide is used as solvent for the solution of the brightenergiven in Example 5.

EXAMPLE 19 To 100 ml. of water are added 0.4 g. of detergent as given inExample 10. A solution is prepared of the optical brightener accordingto Example 5.1 by dissolving 1 g. thereof in 1000 ml. ofdimethylformamide. 2 ml. of this stock solution are added to the abovedescribed washing liquor; this is heated to 60, and 3 g. of nylon fabricare introduced into the solution. The material is treated at thistemperature for 30 minutes. After rinsing and drying, the fabric has abrilliant, white appearance.

Similar results are obtained with the brighteners described in Examples4.2, 4.3 and 5.2, using otherwise the same procedure.

EXAMPLE 20 To 95 ml. of water are added 0.06 ml. of 40% acetic acid and0.06 ml. of alkylpolyglycol ether. A solution is prepared of the opticalbrightener according to Example 5.1 by dissolving 1 g. thereof in 1000ml. of dimethylformamide. An amount of 6 ml. of this stock solution isadded to the above described solution. The aqueous liquor is left for 30minutes at this temperature. The g. of triacetate fabric are introduced.The temperature is raised within 10-15 minutes to 9598 and the liquor isleft at this temperature for minutes. The fabric is then rinsed anddried. The thus treated fabric has a white, brilliant appearance.

EXAMPLE 21 To 95 ml. of water are added 0.06 ml. of acetic acid and 0.06ml. of alkylpolyglycol ether. A solution is prepared of the opticalbrightener according to Example 5.1 by dissolving 1 g. of the saidbrightener in 1000 m1. of dimethylformamide. An amount of 6 ml. of thisstock solution is added to the above described solution. The obtainedliquor is heated to 40 and 3 g. of acetate fabric are introduced. Thetemperature is raised within 1015 minutes to 7580, and the liquor isleft at this temperature for 30 minutes. The fabric is then rinsed withcold water, and dried. The thus treated fabric has a white, brilliantappearance.

Similar results are obtained with the brighteners according to Examples4.2, 4.3, 4.4 and 5.2.

EXAMPLE 22 To 100 ml. of water are added 0.6 ml. of 4% acetic acid and0.06 g. of an alkylpolyglycol ether. A solution is prepared of theoptical brightener described in Example 6.1 by dissolving 1 g. of thesaid brightener in 1000 ml. of dimethylformamide. 6 ml. of this stocksolution are added to the above described aqueous solution. This aqueoussolution containing the brightener is heated to 40; then 3 g. of fabricmade from isotactic polypropylene (Meraklon) are introduced into thesolution. The temperature is raised within 10-15 minutes to 95-98 andthe bath is kept at this temperature for 30 minutes. The fabric isrinsed and dried.

The thus treated fabric has a white, brilliant appearance.

Similar effects are obtained by using, with otherwise the sameprocedure, instead of the stated brightener, identical amounts of thecompound of Example 6.2.

EXAMPLE 23 100 parts of polypropylene with 0.5 part of titanium dioxideand 0.05 part of the optical brightener described in Example 6.1 arehomogenised at 200 in a kneading machine. Under an inert gas at 2-3 atm.and at a temperature of 280-300", the melt is spun, by known methods,through spinning nozzles. The thus obtained polypropylene threads aredistinguished by a high degree of whiteness.

Similar effects are obtained by using, with otherwise the sameprocedure, instead of the above stated brightener, identical amounts ofthe brightener according to Example 6.2.

What we claim is:

1. A benzofuran of Formula I,

R R; R

wherein R represents hydrogen or together with R and the 2 carbon atomsto which R and R are attached, it represents benzene,

R represents hydrogen, halogen, or together with R and the 2 carbonatoms to which R and R are attached, it represents benzene,

R represents hydrogen or alkoxy of 1 to 4 carbon atoms,

R represents hydrogen or halogen,

R represents hydrogen, alkyl of 1 to 4 carbon atoms,

or phenyl,

R stands for the following:

wherein X represents NR,

wherein R stands for hydrogen, alkyl of 1 to 4 carbon atoms,hydroxyalkyl of 1 to 4 carbon atoms, phenyl, benzyl or cyclohexyl, and Rrepresents hydrogen, alkyl of 1 to 4 carbon atoms, alkoxy comprising of1 to 4 carbon atoms, or halogen, and wherein at least one of R R R and Ris a substituent other than hydrogen. 2. A compound according to claim 1wherein R represents hydrogen, chlorine or together with R and the 2carbon atoms to which R and R are attached, it represents benzene Rrepresents hydrogen or methoxy, R represents hydrogen or chlorine, Rrepresents hydrogen, methyl or phenyl, X represents NR, wherein R standsfor hydrogen,

methyl, cyclohexyl, phenyl or benzyl, and R represents hydrogen,chlorine or methyl. 3. A compound according to claim 1 which is na n omo\O \NH 4. A compound according to claim 1 which is ill I) 011.0 0 \N 5.A compound according to claim 1 which is (W1) orno \Q \N 7 18 6. Acompound according to claim 1 which is FOREIGN PATENTS N 1,580,8238/1969 France 260309.2 1,117,000 11/1969 Germany 26'0-309.2 0 1,200,9078/1970 Great Britain 260-3092 01130 \O 5 NATALIE TROUSOF, PrimaryExaminer U.S. Cl. X.R.

References Cited 10 UNITED STATES PATENTS 2528.8, 301.2 W, 301.3 W,260307 D, 307 G, 310 D,

346.2 R 3,103,518 9/1963 Duennenberger et a1.

260-3092 3,497,525 2/ 1970 Harnisch et a1 260309.2

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,772,323 Dated November 13, 1973 Inventofls) HANS SCHLAPFER ET AL It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

I Column 1,- between line 7 (beginning No Drawing and line- 8 (beginning"Int. Cl. insert Claims priority, application Switzerland, June 27,

Signed sealed this 5th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer 7 Commissioner ofPatents FORM PC4050 USCOMM-DC 60376-P69 U 5. GOVERNMENT PRINTING OFFICE:I969 O-36$-JJ4

